Investigating the Emission of Sounds by the Mammalian Ear Using a Computational Model

哺乳动物内耳的功能是探测声音。然而，内耳不仅仅是一个感觉系统；它还可以发出声音，可以通过在耳道中放置麦克风来测量。这些声音被称为耳声发射，通常用于获取内耳功能的间接信息。由于耳声发射测量的无创性和低成本的特点，耳声发射不仅在科学上有应用，而且在新生儿听力筛查测试等临床应用中也有应用。不幸的是，耳声发射的许多方面仍然知之甚少，这限制了从这些测量中获得的信息。该项目旨在对哺乳动物的耳声发射有一个清晰的认识。这项基础研究的结果将有助于改善听力筛选测试、听觉修复和人工耳蜗植入。因此，这个项目可能会产生巨大的社会影响，因为大约有5000万美国人患有不同程度的听力损失。此外，从这项研究中获得的关于听力生物力学的知识将有助于设计模仿内耳功能的新型传感器。该奖项将支持研究生在生物力学、生物物理学、声学和计算建模方面的跨学科培训。这项研究将有来自代表性不足群体的妇女和学生参与，并将传播给更广泛的受众。本研究将集中于一种特殊类型的耳声发射，称为失真产物耳声发射。由于内耳的非线性，畸变产物耳声发射是响应双音刺激而发射的。目前的实验和模型都不能最终确定失真产物耳声发射产生的精确位置。此外，关于畸变产物耳声发射从其产生部位传播到耳道的主要途径存在几种假设。为了解决这些问题，本研究将使用基于生理学的哺乳动物耳朵计算模型，该模型包括其他耳声发射模型中未包含的关键特征。这些模型将中耳的集总参数模型与内耳的三维有限元模型相结合。数值模拟将用于确定耳声发射的产生位置以及它们如何从产生位置传播到耳道。这些理论结果将通过与合作者提供的实验数据的比较来验证和测试。

The function of the mammalian inner ear is to detect sounds. However, the inner ear is not just a sensory system; it can also emit sounds that can be measured by placing a microphone in the ear canal. These sounds, called otoacoustic emissions, are commonly used to obtain indirect information about inner ear function. Because of the noninvasive and low-cost nature of otoacoustic emission measurements, otoacoustic emissions have not only scientific applications but also clinical applications such as newborn hearing screening tests. Unfortunately, many aspects of otoacoustic emissions are still poorly understood, which limits how much information can be obtained from these measurements. This project aims to develop a clear understanding of mammalian otoacoustic emissions. The results from this fundamental research will help to improve hearing screening tests, auditory prostheses and cochlear implants. Hence this project could have a tremendous societal impact since about 50 million Americans suffer from some level of hearing loss. Additionally, the knowledge gained from this research about hearing biomechanics will help to design novel sensors that mimic the function of the inner ear. This award will support the interdisciplinary training of graduate students in biomechanics, biophysics, acoustics and computational modeling. This research will involve participation of women and students from underrepresented groups and will be disseminated to a broader audience.This research will focus on a specific type of otoacoustic emissions, called distortion product otoacoustic emissions. Distortion product otoacoustic emissions are emitted in response to a two-tone stimulus due to the nonlinearity of the inner ear. Current experiments and models are unable to conclusively establish the precise site of generation of distortion product otoacoustic emissions. Furthermore, several hypotheses exist regarding the primary path for the propagation of distortion product otoacoustic emission from their site of generation to the ear canal. To address these questions, this research will use physiologically-based computational models of the mammalian ear that include key features not included in other models of otoacoustic emissions. These models couple a lumped parameter model of the middle ear to three-dimensional finite element models of the inner ear. Numerical simulations will be used to determine where otoacoustic emissions are generated and how they propagate from their site of generation to the ear canal. These theoretical results will be validated and tested by comparison to experimental data provided by collaborators.